Variations of Gas Turbines
There are many variations on simple cycle gas turbines. Each offers something special, be it operating economies or features that meet specific needs. The features might be small size, lightness in weight, high reliability, simplicity, or another measurable attribute. Emphasis is often placed on performance and power density, and achieving these objectives through use of known technologies and sound design principles for compressors, turbines, combustors, heat exchangers, and technology from related conventional materials sciences would be desirable. It is expected that achieving large gains requires the component arrangement to be new and different, to depart significantly from conventional designs. Any departure that results in an increase in complexity also has to significantly improve performance to be commercially useful; the more the departure, the more attractive the gains have to be.
Without question, component research and development efforts over recent years have served well to define advanced levels of aerodynamic and thermodynamic component efficiency. By combining these advances with similar gains in materials sciences and cooling technologies, capability now exists to design for high stage pressure ratios and high operating temperatures. But adopting an approach that would capture the full range of these advances would be very costly and would involve undesirably high risks. What is needed are the benefits to be derived from a new flow-path arrangement, rather than high stage loadings, high temperatures, and high stresses.
Fundamental Combustion Characteristics of Fuels.
For most gaseous fuels, the products of complete combustion are carbon dioxide and water (in the form of water vapor). Depending on content, small amounts of sulphur dioxide can be produced, along with other gaseous products. However, the most significant products of combustion, by far, will be carbon dioxide and water. The rest, for the purpose of this discussion, can be ignored. The most important fundamental result is that for every pound of fuel burned, in combination with the ambient air used to support combustion, the gases produced will contain as much as 2.25 pounds of water vapor and up to 2.75 pounds of carbon dioxide. Until now, it does not appear that any attention has been given to recovering any of the products of this combustion, let alone recovery of the exhaust water. Fruitful human endeavors have always depended upon a readily available water supply. What is desirable, and what would be different from any other power producing system, is a power producing system from which exhaust gas water may readily be recovered. What is needed is a source of water that generates power efficiently, particularly in drought-ridden areas or desert regions; what is needed is an engine design for applications in developing regions that need two vital commodities: water and power. What is needed is a design that is independent of geographical location, climate, or changing meteorological conditions, but which does not have a negative impact on other engine favorable operating characteristics.